Get started with these instructions
Browse some themes for inspiration: https://firefoxcss-store.github.io/
Grab snippets of code from these recipes: https://github.com/Timvde/UserChrome-Tweaks
Get more advice here: https://www.userchrome.org/
-
In
about:config
ensure thatdevtools.chrome.enabled
istrue
-
Open the Browser Console (not DevTools) with Ctrl-Shift-J on Windows/Linux
-
Run the following code:
AddonManager.getActiveAddons().then(({addons}) => {
for (let addon of addons) {
if (addon.type === "extension" && addon.isSystem === false && addon.hidden === false) addon.reload();
}
});
Source: https://www.reddit.com/r/firefox/comments/wqneq9/comment/iko4bl4/